A5019839031- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Earthquake Detection and Analysis
- Astro and Planetary Science
- Planetary Science and Exploration
- GNSS positioning and interference
- Geomagnetism and Paleomagnetism Studies
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Space Science and Extraterrestrial Life
- earthquake and tectonic studies
- Seismic Waves and Analysis
- Methane Hydrates and Related Phenomena
- Stellar, planetary, and galactic studies
- Meteorological Phenomena and Simulations
- Marine and environmental studies
- Metallurgical Processes and Thermodynamics
- Electrohydrodynamics and Fluid Dynamics
- Spacecraft Design and Technology
- Radio Wave Propagation Studies
- Gas Dynamics and Kinetic Theory
- Oceanographic and Atmospheric Processes
- Spaceflight effects on biology
- Ocean Waves and Remote Sensing
- Tropical and Extratropical Cyclones Research
National Institute of Information and Communications Technology
2015-2024
Kyushu University
2009-2024
National Institute on Consumer Education
2023
Institute of Information and Communication Technologies
2023
GFZ Helmholtz Centre for Geosciences
2021
University of Potsdam
2021
Seikei University
2020
Nagoya University
2000-2014
Shinshu University
2010
University of Alabama in Huntsville
2010
This paper compares results from a whole atmosphere‐ionosphere coupled model, GAIA, with the COSMIC and TIMED/SABER observations during 2008/2009 northern winter season. The GAIA model has assimilated meteorological reanalysis data by nudging method. comparison shows general agreement in major features stratosphere to ionosphere including growth decay of stratospheric sudden warming (SSW) event 2009. During this period, pronounced semidiurnal variation F region electron density its...
The existence of a small intrinsic magnetic field at Mars is still being debated. ion densities, measured in the Martian ionosphere above 300 km by retarding potential analyzers on Viking landers, are very low (Hanson et al., 1977). ionospheric thermal pressure insufficient itself to withstand solar wind dynamic pressure, suggesting presence and Mantas, 1988). However, two types possible: (1) weak field, or (2) an induced driven interaction with Mars. latter situation analogous Venus during...
[1] This paper introduces a new Earth's atmosphere-ionosphere coupled model that treats seamlessly the neutral atmospheric region from troposphere to thermosphere as well thermosphere-ionosphere interaction including electrodynamics self-consistently. The is especially useful for study of vertical connection between meteorological phenomena and upper behaviors. As an initial simulation using model, we have carried out 30 day consecutive run in September. result reveals longitudinal structure...
The present study compares simulations of the 2009 sudden stratospheric warming (SSW) from four different whole atmosphere models. models included in comparison are Ground‐to‐topside model Atmosphere and Ionosphere for Aeronomy, Hamburg Model Neutral Ionized Atmosphere, Whole Model, Community Climate Extended version (WACCM‐X). focuses on zonal mean, planetary wave, tidal variability middle upper during SSW. constrained lower atmosphere, simulated mean wave is thus similar up to ∼1 hPa (50...
Abstract A new three‐dimensional high‐resolution numerical model to study equatorial plasma bubble (EPB) has been developed. The High‐Resolution Bubble (HIRB) is developed in a magnetic dipole coordinate system for the and low‐latitude ionosphere with spatial resolution of as fine 1 km. Adopting higher‐order scheme than those used existing models, HIRB capable reproducing bifurcation, pinching, turbulent structures EPB. From seeding perturbation resembling large‐scale wave structure (LSWS),...
Abstract The wind shear theory is widely accepted as an explanation for the formation of a sporadic E (Es) layer, but direct comparison Es with local has been limited due to lack neutral measurements. This study examines role vertical Es, using signal‐to‐noise ratio profiles from COSMIC‐2 radio occultation measurements and concurrent Ionospheric Connection Explorer. It observed that occurrence rate average S4 index are correlated negative eastward wind, providing observational support...
The Kelvin–Helmholtz (K‐H) instability at the Venus ionopause is investigated using a two‐dimensional global hybrid (particle ions, massless fluid electrons) model for case where interplanetary field oriented transverse to flow. In order self‐consistently study kinetic processes ionopause, we calculate entire ionopause–solar wind interaction region kinetically, including ionosphere, transition layer, magnetosheath, and solar regions, by applying boundary‐fitted coordinates particle‐in‐cell...
The global wave number 4 longitudinal structure of ionospheric density has been observed recently by a satellite measurements and considered as signature dynamical coupling from the deep atmosphere to ionosphere. By using numerical model atmospheric electrodynamics with input fields whole general circulation an ionosphere‐thermosphere model, we investigated generation mechanism for F‐region zonal electric field (vertical E × B drift) possible driver variation, especially respect eastward 3...
We develop a realistic and time-varying model that satisfies both the Voyager 1 (V1) 2 (V2) observed crossing times locations of termination shock (TS) simultaneously by performing three-dimensional (3D) magnetohydrodynamic (MHD) simulations using total variation diminishing (TVD) scheme includes effects neutral particles. Daily values solar-wind speed density V2 are used at every simulation step so short-term dynamical reproduced. Before dynamic simulation, we generate 3D stationary...
In the framework of integrated numerical space weather prediction, we have developed a 3‐D MHD simulation model solar surface‐solar wind system. We report construction method and its first results. By implementing grid system with angularly unstructured increasing radial spacing, realized spherical that has no pole singularity fine size around inner boundary wide‐range up to 1 AU simultaneously. The magnetic field at is specified by observational data. order obtain supersonic speed,...
The upper limits of the ion pickup and cold outflow loss rates from early martian atmosphere shortly after Sun arrived at Zero-Age-Main-Sequence (ZAMS) were investigated. We applied a comprehensive 3-D multi-species magnetohydrodynamic (MHD) model to an CO2-rich atmosphere, which was assumed have been exposed solar XUV [X-ray extreme ultraviolet (EUV)] flux that 100 times higher than today wind about 300 denser. also late onset planetary magnetic dynamo, so Mars had no strong intrinsic field...
Numerical simulations are performed to simulate atmospheric perturbations observed at ionospheric heights just after the 2011 off Pacific coast of Tohoku Earthquake. A time-dependent, two-dimensional, nonlinear, non-hydrostatic, compressible and neutral, numerical model is developed reproduce perturbations. An impulsive upward surface motion assumed as source Simulated 300-km altitude show remarkable agreement with oscillations in total electron content (TEC) when width about 250 km. In...
Abstract In order to study the dynamical role of gravity waves (GWs) propagating upward from lower atmosphere thermosphere, numerical simulation using a high‐resolution general circulation model that contains region ground surface exobase (about 500 km height) has been performed. Our results indicate zonal momentum drag due breaking/dissipation GWs (GW drag) plays an important not only in mesosphere but also thermosphere. particular, GW at high latitudes the150–250 height exceeds 200 ms −1...
Abstract There have been a number of papers reporting that the statistical occurrence rate sporadic E ( s ) layer depends not only on local time and season but also geographical location, implying seasonal dependence in vertical neutral wind shear is one factors responsible for occurrences rate. To study role global distribution rate, we employ self‐consistent atmosphere‐ionosphere coupled model called GAIA (Ground‐to‐topside Atmosphere Ionosphere Aeronomy), which incorporates meteorological...
Abstract The volcano of Hunga Tonga-Hunga Ha ’ apai in Tonga erupted on 15 January 2022, generating severe disturbances the atmosphere and ionosphere. This event provided us with large amount data ionosphere, various kinds observational studies have been made. Recently several simulation also made to reproduce understand atmosphere–ionosphere variations driven by volcanic eruption. Although reproduced global ionosphere successfully, phenomena related acoustic waves not fully investigated. We...
A long period Pc5 pulsation was observed at Phimai in Thailand, shortly after the origin time of Sumatra earthquake on December 26, 2004. The localized nature and oscillations suggest that magnetic generated by dynamo action lower ionosphere, set up an atmospheric pressure pulse which propagated vertically as acoustic wave when ocean floor suddenly moved vertically. It is speculated a Pc3 type Tong Hai China, 10 degrees north latitude, result field line resonance with magneto‐sonic from...
Abstract In the Sumatra earthquake that occurred on December 26, 2004, significant ionospheric variations were detected immediately after in both TEC (total electron content) data of GPS (Global Positioning System) and ionosonde data. A magnetic pulsation with a period about 4 min was also observed Phimai, Thailand. Recent studies have suggested these events are associated acoustic waves excited by sudden large-scale displacement sea surface around epicenter. order to study phenomena...
The substorm mechanism is investigated by analyzing the numerical results obtained through use of recently refined magnetohydrodynamic model. After showing growth phase features, solution reproduces observed signatures a onset, including formation near‐Earth neutral line (NENL), earthward directed flow in plasma sheet, dipolarization, geosynchronous D deflection, development nightside field aligned currents (FACs), and electrojets ionosphere. onset triggered sudden collapse sheet successive...
Abstract The whole atmosphere model GAIA is employed to shed light on atmospheric response the 2009 major stratosphere sudden warming (SSW) from ground exobase. Distinct features are revealed about SSW impacts thermospheric temperature and density above 100 km altitude. (1) effect primarily quasi‐semidiurnal in tropical regions, with noon pre‐midnight sectors cooling dawn dusk sectors. (2) This pattern exists at all altitudes km, its phase being almost constant 200 but propagates downward...
This paper for the first time presents a detailed comparison between simulated and observed global electron density responses to different atmospheric tides forced from below. The recently developed Earth's whole model troposphere ionosphere, called GAIA, has been used simulation of tidal responses. They have compared with extracted COSMIC data period October 2007 March 2009. Particular attention paid nonmigrating DE3/DE2 migrating DW1, SW2 TW3 GAIA reproduced quite well Both simulations...
Abstract Changes of the zonal mean state thermosphere during 2009 stratospheric sudden warming (SSW) have been investigated using Ground‐to‐topside model Atmosphere and Ionosphere for Aeronomy (GAIA) model. Both thermal dynamical structure exhibit pronounced changes SSW in terms temperature winds. First, above 100 km altitude drops at all latitudes except a narrow band around 60°N. Such perturbations are found to be dominantly caused by direct heating/cooling processes related solar...
Abstract Using a global atmosphere‐ionosphere coupled model, the characteristics and excitation source of traveling ionospheric disturbances (TIDs) during geomagnetically quiet periods are studied. This is first paper concerning simulation TIDs generated by upward propagating gravity waves (GWs) that spontaneously in model. The dominant horizontal wavelengths simulated range from 700 to 1,500 km. phase velocities 45–90 min 250–300 m s −1 , respectively. These features same as those GWs km...